Topic
Pyranose
About: Pyranose is a research topic. Over the lifetime, 1619 publications have been published within this topic receiving 35348 citations. The topic is also known as: pyranoses & hexopyranose.
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TL;DR: In this article, a synthesis of 5-thio-D -galactose, in the form of its crystalline, anomeric methyl glycopyranosides, is described.
34 citations
TL;DR: In this article, a new type of carbohydrate-based bisoxazoline ligands was prepared from inexpensive D-glucosamine and tested in asymmetric cyclopropanation reactions.
34 citations
TL;DR: In this paper, the dioxime was coordinated to the Ca, Cd, Co (II), Cu, Fe, Mg, Mn, Ni, Pb, and Zn ions.
34 citations
TL;DR: This finding rationalizes the different methyl α- and β-L-idopyranoside (3)J(H,H) values and facilitates engineering of biologically and commercially important derivatives and underpins deciphering presently elusive structure-function relationships in the glycome.
Abstract: In the aldohexopyranose idose, the unique presence of three axial ring hydroxyl groups causes considerable conformational flexibility, rendering it challenging to study experimentally and an excellent model for rationalizing the relationship between puckering and anomeric configuration. Puckering in methyl α- and β-l-idopyranosides was predicted from kinetically rigorous 10 μs simulations using GLYCAM11 and three explicit water models (TIP3P, TIP4P, and TIP4P-EW). In each case, computed pyranose ring three-bond (vicinal) 1H–1H spin couplings (3JH,H) trended with NMR measurements. These values, calculated puckering exchange rates and free energies, were independent of the water model. The α- and β-anomers were 1C4 chairs for 85 and >99% of their respective trajectories and underwent 1C4→4C1 exchange at rates of 20 μs–1 and 1 μs–1. Computed α-anomer 1C4↔4C1 puckering rates depended on the exocyclic C6 substituent, comparing hydroxymethyl with carboxyl from previous work. The slower kinetics and restricted p...
33 citations
TL;DR: Results indicate that beta-galactosidase probably destabilizes its substrate into a planar conformation of some type and that the galactose in the transition state may, therefore, also be quite planar.
Abstract: Various sugars and their lactones were tested for their inhibition of beta-galactosidase (Escherichia coli). L-Ribose, which in the furanose form has a hydroxyl configuration similar to that of D-galactose at positions equivalent to the 3- and 4-positions of D-galactose, was a very strong inhibitor, and D-lyxose, which in the furanose form also resembles D-galactose, was a much better inhibitor than expected. Structural comparisons prelude the pyranose forms of these sugars from being significant contributors to the inhibition, and inhibition at different temperatures (at which there are different furanose concentrations) strongly supported the conclusion that the furanose form is inhibitory. Studies with sugar derivatives that can only be in the furanose form also supported the conclusion. This is the first report of the inhibitory effect of furanose on beta-galactosidase. Lactones were also inhibitory. Every lactone tested was much more inhibitory than was its parent sugar. D-Galactonolactone was especially good. Experiments indicated that it was D-galactono-1,5-lactone rather than D-galactono-1,4-lactone which was inhibitory. Inhibition of beta-galactosidases from mammalian sources by lactones has been reported previously, but this is the first report of the effect of beta-galactosidase from E. coli. Since furanoses in the envelope form are analogous (in some ways) to half-chair or sofa conformations and since lactones with six-membered rings probably have half-chair or sofa conformations, the results indicate that beta-galactosidase probably destabilizes its substrate into a planar conformation of some type and that the galactose in the transition state may, therefore, also be quite planar.(ABSTRACT TRUNCATED AT 250 WORDS)
33 citations